Method for using molten metal channel for the conveyance of liquid glass

ABSTRACT

The method disclosed pertains to making glass sheets by placing molten glass on a molten metal bath in a channel which communicates with chambers on the sides of the channel which allows molten metal to flow from the chambers. The temperature of the molten glass is regulated within adjustable blocks on the sides of the channel.

United States Patent 1191 Classen Mar. 19, 1974 METHOD FOR USING MOLTENMETAL 3.433.612 3/1969 Dickinson et al 65/99 A I 2: CHANNEL FOR THECONVEYANCE 0 3.525.601 8/1970 Ohsato 65/99 A X LIQUID GLASS 3.533.71310/1970 Fuimoto at al. 65/99 A x T l 3,647,408 3/1972 Dickinson 65/99 A1 [76] Inventor: Franz Classen, Kamatr, 36, 505 3,684,475 8/1972Bondarev et al 65/99 A X [22] Filed: June 8, 1972 PrimaryExaminer-Robert L. Lind say, Jr.

Attorney, Agent, or Fzrm-Wemer, Basile and [21] Appl. No.: 261,114Weintraub Related US. Application Data [62] Division of Ser. No.209,892. Dec. 20, I971. [57] ABSTRACT The method disclosed pertains tomaking glass sheets (g1 65/99 A, 65/lC gb i 833g by placing molten glasson a molten metal bath in a [58] 'Li 186 324 channel which communicateswith chambers on the o a c 65/34 sides of the channel which allowsmolten metal to flow from the chambers. The temperature of the molten I5 6] References Cited glfatszscileggzted w1th1n ad ustable blocks on thes1des UNITED STATES PATENTS 3.231.351 1/1966 Birchard 65/182 R x 4 Chin,3

l8 [6 Q 4 I8 I 111 A 2// 6 I? 51 5 "25 '1- .f. i 4* "I; :1 f

' %J- I- :I- 1.- 1 2 -21;- 1- F7 Ponz-Grengel, Germany PAIENIEI] MAR I 9I974 SHEET 1 OF 2 U om PATENTEI] MR 1 9 I974 SHEET 2 [1F 2 METHOD FORUSING MOLTEN METAL I CHANNEL FOR THE CONVEYANCE OF LIQUID GLASS This isa division, of application Ser. No. 209,892 filed Dec. 20, 197i.

in the case of most methods for processing molten glass the glass whichhas been produced in a glass melting furnace is supplied to the furtherprocessing apparatus or station via a so-called channel or feeder. Thisis the case both in classical and in more modern methods for theproduction of an endless glass strip, such as in casting glassprocesses, plate glass making processes and, more particularly, in thefloat glass process.

Generally, the channel has to fulfill various requirements. On the onehand within the channel or feeder the rate of flow must be controlled sothat a constant quantity of glass per unit time is supplied to theworking station. On the other hand, the glass stream in the channel orfeeder must be reduced to a certain predetermined optimum width. it hasthus been found, in the case of the production of float glass, that forthe homogeneity of the eventual glass strip the flow characteristics inthe channel or feeder play a predominant role, and that for eachparticular plant and each particular rate of melting specific flowconditions are necessary in order to achieve optimum results. The flowcharacteristics in the channel are furthermore influenced substantiallyby the temperature obtained in the channel and by the shape of thechannel. The optimum shape can only be computed with difficulty andinstead must be determined on the basis of practical experience.Furthermore, the channel has to fulfill the requirement of providing aregulating effect on the temperature of the glass flow which must haveits temperature kept within comparatively close tolerances.

Known channel constructions are generally rigid, i.e., they cannotreadily be adapted to suit optimum conditions. As regards temperatureregulation in the glass flow there is a certain disadvantage in thattime elapses before the temperature of the glass is changed because thesupply or removal of heat is substantially only through the upper faceof the glass. This is because abrupt local cooling has a disadvantageouseffect on the quality of the glass. in the case of known arrangements,therefore, the transfer of heat is carried out by means of radiation. Asregards the narrowing or pinching out of the glass flow, the knownconstructions cannot readily provide for changes.

One object of the invention is to overcome these disadvantages in knownchannel or feeder constructions.

A further object of the invention is to provide a feeder or channelwhich has a wide range of application and provides for an enhancedconditioning of the glass stream in it. Furthermore, the invention isintended to provide for an improved apparatus for varying the lateralflow delimiting means and thus for adjusting the effective cross sectionof the channel.

Accordingly the present invention consists in a glass channel forconveying molten glass, the channel comprising a bottom whose surface isat least partially constituted by the surface of a bath of molten metal,such as tin, whose temperature can be regulated.

in accordance with a first embodiment of a channel or feeder inaccordance with the invention it is not only possible to achieve anexcellent conditioning of the glass stream, but it is also possible evento regulate the speed of flow of the quantity of glass passing along thefeeder exclusively by varying the viscosity of the glass melt bychanging the temperature of the metal bath. For this purpose use can bemade of known arrangements so as to influence the temperature of theglass flow and thus vary the speed of movement. However, the device orapparatus in accordance with the invention constitutes additionally aparticularly effective and simple construction. its particularadvantages lie in that the liquid metal path, owing to its large surfacearea, its high thermal conductivity, and its intimate contact with theglass melt, provides for an effective and even removal of heat, withoutan abrupt and local cooling effect being exerted on the glass, which, ashas already been mentioned, leads to flaws in the glass. in order toregulate the temperature of the tin bath heating and/or cooling devicescan be provided which act on the tin bath.

In accordance with a particularly convenient embodiment of the inventionchambers are provided to the sides of the channel which arehydraulically connected with the tin bath inside the channel, and thecooling and/or heating devices are provided in the chambers. In thisarrangement it is possible in principle to ensure that a glass layer isarranged on the tin bath inside these chambers so that additional meansfor protecting the tin bath against oxidation is not necessary.

If required the effect, of the metal bath on the glass can be amplifiedby heating and/or cooling elements arranged above the glass stream.

in accordance with a particularly convenient embodiment of the inventionlateral limiting blocks for the glass stream or flow are provided withinthe channel and are immersed in the tin bath toward the outlet end ofthe channel. Owing to the fact that these limiting blocks float in thetin bath their position can be readily arranged and the pinching out ofthe glass flow or stream in order to make it narrower can be varied asdesired to achieve optimum results. a

in accordance with a further feature of the inventio the limiting blockscan be provided with setting means extending to outside the channel sothat the desired change in the position of the limiting blocks duringoperation is further simplified. The height of the glass flow above thetin bath can in turn be changed by varying the level of the tin bath. inthis manner the flow pattern within the channel can be furthermoreinfluenced and it is possible to convey particular layers of the glassfaster than other layers.

The invention is now described in more detail with reference to theaccompanying drawings.

FIG. 1 shows a first embodiment of the invention in its simplest form,in vertical longitudinal section.

FIG. 2 is a horizontal section through a second embodiment of a channelin accordance with the invention.

FIG. 3 is a vertical section on the line lI-ll through the channel orfeeder shown in FIG. 2.

in the glass melting tank 1 melting of the glass takes place. The glassmelt 2 is supplied to a roll stand or a float glass installation denotedby reference numeral 7, through a channel 6 delimited by the roof 3 andthe side walls 4 and 5.

The bottom of the channel 6 is formed by a container 14. of refractorymaterial, ending with the level of the cooling elements 16 and [7. Theheating and cooling elements 16 and 17 can be conventional electricalheating arrangements,;induction heating arrangements, or coolantcarrying tubes or the like as will be familiar to those in the art. Inthecase of the embodiment of the invention shown in FIGS. 2 and 3 theheating and cooling elements 16 and 17 are not arranged in the actualspace within the channel itself, that is to say below the glass melt 2,but disposed above the molten glass in the chambers 18 communicatingwith the longitudinal sides of the channel. These chambers hydraulicallycommunicate with the channel of the actual tin bath container 14 and toa certain extent fulfill the function of a heat exchanger. Thearrangement of the cooling arrangement outside the actual channel hasthe advantage among others that the removal of gas occurring with acooling of the liquid tin does not lead to flaws in the glass stream dueto bubble formation.

Following the channel a conventional vertically moving regulating slide28 can be provided in order to regu late the rate of flow through thechannel. it is also possible, as is shown in the figures, to dispensecompletely with a regulating slide and, owing to the excellent thermalconductivity properties of the liquid metal bath within the channel, tocontrol the rate of flow exclusively by regulation of the temperature ofthe tin bath 15, providing there is a sufficient cooling of the tin baththe viscosity of the glass melt in the direction of flow of the glassmelt increases in accordance with the degree of removal of heat throughthe tin bath and the rate of flow is decreased in accordance with theincrease in the viscosity. A rate of flow is reached which bears adefinite relationship to the degree of heatremoval by the tin bath 15.Since in the temperature range in question the viscosity of the glassvaries considerably, comparatively small alterations in temperature ofthe tin bath 15 are sufficient to achieve a good regulation of the rateof flow of the glass flowing through the channel or feeder.

Above the tin bath 15 it is also possible to provide coolers 21extending over the glass stream. The coolers 21 are put into operationwhen it is required to provide an increased cooling of the tin bath 15.Furthermore,

for controlling the temperature in the channel or feeder it is alsopossible to provide additionally electrical heating elements 22 disposedabove the glassstream or flow.

As can be seen from FIGS. 2 and 3, adjustable lateral limiting blocks 25including first and second pivotally attached sections are providedwithin container 14 toward the outlet end of the channel 6 in the caseofthis embodiment of the invention. The limiting blocks 25 are disposed oneach longitudinal edge of the molten glass stream and float in the tinbath [5 toward the outlet end of the channel 6. They are held in theposition required by linkages 26,'which pass through suitably sealed offopenings 27 to the outside, and since the linkages 26 are operated fromoutside the channel, adjustment of the position of the limiting blockscan readily be carried out at any time. Owing to the arrangement ofthese floating limiting blocks 25 and to the subdivision which may becarried out if necessary, both the final breadth of the pinched glassstream and also the extent along which the glass stream is narrowed, canbe changed within wide limits. The limiting blocks 25 can be providedwith heating means 29 for heating at least those surfaces of theselimiting blocks which come in contact with the lateral edges of theglass stream in order to reduce friction between the glass stream andthe block faces which it contacts. The glass melt 2 flows into. thechambers 18 where it spreads out on the tin bath and protects the tinagainst oxidation.

if desired it is also possible to provide partition walls 30 within thetin bath 15 extending perpendicularly to the direction of flow of theglass melt 2. These walls divide up the tin bath into several sequentialmore or less separated sections. Such a subdivision has the advantage ofmaking it possible to regulate the temperature of the tin bath withinthe individual sections so that a controlled removal of heat from theunderside of the glass layer can be achieved.

I claim:

1. A method for supplying glass from a furnace to a float glass makinginstallation, comprising the steps of:

placing molten glass on to a molten metal bath in a channel and on twochambers, each of the chambers communicating with a different one of thelongitudinal sides of said channel, said chambers functioning as a heatexchanger for said channel;

hydraulically communicating the chamberswith the channel to allow theflow of a portion of the molten metal bath and the molten glasssupported thereon to pass therethrough;

regulating the temperature of said molten glass in said channel withheating and cooling means disposed above the molten glass stream in thechannel;

regulating the temperature of said molten glass in said chambers, withheating and cooling means disposed above the molten glass in thechambers; thus, preventing flaws in said glass in said chamber due tobubble formations formed by gases emanating from said molten metal bathin said chambers;

positioning adjustable lateral limiting blocks at an outlet end of thechannel on each longitudinal edge of the molten glass stream in thechannel to adjust the width of said molten glass as it flows through tosaid channel.

2. The method of claim 1,;characterized by:

regulating the temperature of said molten metal both to vary theviscosity of said molten metal and thereby regulate the speed of flow ofsaid molten glass over said molten metal bath.

3. The method substantially as set forth in claim 1,

characterized by:

adjusting the width of said molten glass as it exits from said channelto regulate the final breadth of said glass.

4. The method of claim 1 which includes the step of:

the lateral limiting blocks.

'- t s s s e

1. A method for supplying glass from a furnace to a float glass makinginstallation, comprising the steps of: placing molten glass on to amolten metal bath in a channel and on two chambers, each of the chamberscommunicating with a different one of the longitudinal sides of saidchannel, said chambers functioning as a heat exchanger for said channel;hydraulically communicating the chambers with the channel to allow theflow of a portion of the molten metal bath and the molten glasssupported thereon to pass therethrough; regulating the temperature ofsaid molten glass in said channel with heating and cooling meansdisposed above the molten glass stream in the channel; regulating thetemperature of said molten glass in said chambers, with heating andcooling means disposed above the molten glass in the chambers; thus,preventing flaws in said glass in said chamber due to bubble formationsformed by gases emanating from said molten metal bath in said chambers;positioning adjustable lateral limiting blocks at an outlet end of thechannel on each longitudinal edge of the molten glass stream in thechannel to adjust the width of said molten glass as it flows through tosaid channel.
 2. The method of claim 1, characterized by: regulating thetemperature of said molten metal both to vary the viscosity of saidmolten metal and thereby regulate the speed of flow of said molten glassover said molten metal bath.
 3. The method substantially as set forth inclaim 1, characterized by: adjusting the width of said molten glass asit exits from said channel to regulate the final breadth of said glass.4. The method of claim 1 which includes the step of: heating the laterallimiting blocks to heat the lateral edges of said molten glass stream incontact with the lateral limiting blocks.